Nadella takes over a huge and successful company with a lot of issues that need fixing from its culture to its position in mobile.

In an interview with the New York Times Adam Bryant, Nadella said Ballmer taught him two things: 1) He should never compare himself to others, and 2) he never needs to ask how he's doing. If he's not doing a good job, he'll know.

Here's what Nadella said.

"I remember asking [Ballmer]: “What do you think? How am I doing?” Then he said: “Look, you will know it, I will know it, and it will be in the air. So you don’t have to ask me, ‘How am I doing?’ At your level, it’s going to be fairly implicit.”

I went on to ask him, “How do I compare to the people who had my role before me?” And Steve said: “Who cares? The context is so different. The only thing that matters to me is what you do with the cards you’ve been dealt now. ... The lesson was that you have to stay grounded, and to be brutally honest with yourself on where you stand."